Nitrated cellulose and method of producing



Patented Apr. 30, 1935 UNITED STATES PATENT OFFICE NITRATED GELLULOSE AND METHOD OF PRODUCING N Drawing Application February 27, 1934,

Serial No. 713,138 I 10 Claims. (01. 260-446) This invention relates to an improvement in Wood pulp and in nitrated derivatives thereof and method of production.

The object of this invention is to produce, more particularly from yellow pine wood a fibre or pulp of high alphacellulose content and of such physical character as to enable its ready and uniform nitration by well known methods involving mixtures of nitric and sulphuric acid ordinarily used.

More particularly, the object of this invention is to produce a wood fibre which will be easily penetrable by the nitrating mixture and which, at the same time, will contain a minimum amount of soda-soluble impurities. Heretofore various attempts have been made to produce a pulp more especially for use in the production of nitrated derivatives, as nitrocellulose, from wood and various woods have been treated by various methods to that end. However, none of the methods heretofore attempted have been productive of a wood pulp or fibre which has had the desired characteristics.

Among the various attempts which have been made to produce a wood pulp or fibre possessing the characteristics indicated and adaptable for the production of, for example, nitrated cellulose, it has been suggested that the wood pulp be mixed with cotton lint prior to drying and nitration in order to have the wood fibres opened up sufficiently to permit nitrating acid to act freely and uniformly on the fibres or, in other words, to prevent the formation of hard compact lumps of fibre on drying. Such procedure is describedmore in detail in the United States patent to Broadbent, No. 1,567,330, dated September 2, 1924. Another procedure is described in the United States patent to Richter, et al., No. 1,729,628, which in brief suggests a treatment of wood pulp adapted for nitration involving coating the fibres with some material, as cellulose xanthate, cellulose nitrate, or the like, in order to inhibit absorption and decrease penetrability, and further states that it is desirable to hydrate the pulp or fibre to a considerable degree in order to decrease its penetrability.

In accordance with this invention, as has been indicated, the object is to increase to a large degree the penetrability of the pulp or fibre in order to permit maximum penetration by the nitrating acids and enable uniform nitration. Thus, this invention is differentiated sharply from the procedures such as above referred to by the increase in the absorptiveness and penetrability of the pulp or fibre obtained as compared with coating process.

of the fibre and in the avoidance of hydration of the pulp or fibre.

This invention is further differentiated sharply from the prior art by the fact that the pulp or fibre contemplated is produced from southern 5 yellow pine wood, jack pine, loblolly pine, spruce, or the like, not heretofore contemplated as a source of cellulose, for the production of nitrated derivatives. 7

In carrying out the method embodying this in- 10 vention the yellow pine wood used may be and desirablyis stump wood, downwood and the like. The cost of the nitrated cellulose is substantially reduced by the value of the by-products, as rosin, turpentine and pine oil, which are recovered. 15

In accordance with this invention the nitrated cellulose contemplated is produced by the treatment of yellow pine wood, or equivalently, jack pine, loblolly :pine, spruce, or the like, suitably chipped, for the extraction of rosin, turpentine 20 and pine oil encrusting materials, coloring matter, soda soluble components, etc., with the production of a pulp high in alpha-cellulose content. Such pulp is dewatered by squeezing, picked andthen finally dried by heating and the 25 non-hydrated, flufied fibre nitrated, using any desired nitrating mixture.

If desired, the pulp, containing suflicient water, may be formed into sheets, preferably about two inches thick, on a rotary vacuum screen without roll pressure. The sheet when formed is stripped from the rotary screen and without rolling is dried, preferably at a low heat, picked apart and then nitrated.

As a specific illustration of the procedure in accordance with this invention for the production of the contemplated nitrated cellulose, yellow pine wood, which may be long leaf southern pine, and will preferably be dead wood, as stumps, downwood, etc., is first suitably chipped and 0 screened to remove sand, charcoal, rotten wood, etc. The chips are then treated for the removal of turpentine and part of the pine oil content, as for example, by steam distillation. The rosin and remaining pine oil are then extracted from the chips with a solvent, for example, with gasoline. With extraction of the rosin, coloring material contained in the wood will be largely removed, as indicated by the dark color of the rosin. The extracted chips are treated for removal of the solvent, screened and then digested, preferably by the well known sulphate The pulp produced is screened, washed, bleached with chlorine,'washed and then given a hypochlorite bleach. The bleached wood is then treated with a cold aqueous caustic soda solution, say a 9%-17% caustic solution, to par tially mercerize it and render it absorbent and fluliy, to dissolve out encrusting materials and decrease the soda-soluble components, thus raising the resistant alpha-cellulose content. A large volume of water is then added to the pulp, in amount to thoroughly disperse it, say an amount to bring it to about a 45% consistency and the caustic washed out with agitation of the pulp. The resultant pulp is then desirably further bleached with, for example, a 1.5% (by weight on the pulp) calcium hypochlorite solution at, say C. for about an hour, then washed and then treated with oxalic acid or sodium fluoride and a mineral acid, as for example, sulphuric acid, for about an hour at a temperature of about 65 C. to remove ash, as iron or the like compounds. The pulp is then washed,'dewatered toabout a 62% water content by passing between squeeze rolls under pressure, picked and dried with the production of a non-hydrated fiuffy fibre. The method of drying the pulp in accordance with this invention involves drying at a relatively low temperature, say about 150 F.-240 F.

If desired the pulp may be sheeted in a loose sheet on a vacuum screen, then dried, picked and nitrated, as has been indicated.

The pulp, as has been indicated, will be high in alpha-cellulose content, will be of loose texture, of desirable absorbency and the fibres will be unhardened. The pulp so produced may, as has been indicated, be uniformly and completely nitrated by any usual nitrating method withthe production of a nitrated cellulose of goodcolor and which will give a clear solution free of cloud or unnitrated particles. I V

This application is acontinuation in part of the application filed by us Serial No. 543,158, filed June 9, 1931.

What we claim and, desire to protect by Letters Patent is:

1. The method of producing nitrated cellulose from wood which includes extracting the wood with a solvent for components of the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, dewatering the pulp, picking the pulp, drying Without subjecting the pulp to any substantial pressure and then nitrating the pulp.

2. The method of producing nitrated cellulose from resinous wood which includes extracting the wood with a solvent for resinous components thereof, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, dewatering the pulp, picking the pulp, drying without subjecting the pulp to any substantial pressure and then ,nitrating the pulp.

3. The method of producing nitrated cellulose from pine wood which includes extracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, dewatering the pulp, picking the pulp, drying without subjecting the pulp to any substantial pressure and then nitrating the pulp.

4. The method of producing nitrated cellulose from yellow pine wood which includes extracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, rebleaching the pulp, dewatering the pulp, picking the pulp, drying without subjecting'the pulp to any substantial pressure and then nitrating the pulp.

5. The method of producing nitrated cellulose from yellow pine wood which includes extracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, rebleaching the pulp, forming the pulp into a loose sheet, picking the pulp, drying the sheet without any substantial pressure, picking the sheet and nitrating the pulp;

6. The method of producing nitrated cellulose from yellow pine wood which includesextracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleachingthe pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, rebleaching the pulp, treating the pulp for the removal of ash, dewatering the pulp, picking the pulp, drying without subjecting the pulp to any substantial pressure and then nitrating the pulp.

7. The method of producing a pulp high in alpha-cellulose from yellow pine wood which includes extracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, dewatering the pulp, pickin g the pulp, drying without subjecting the pulp 'to any substantial pressure and then nitrating-the p p.

8. The method of producing nitrated cellulose from yellow pine wood which includes extracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp,

treating the pulp with oxalic and sulphuric acids for the removal of ash therefrom, dewatering the pulp, picking the pulp, drying without subjecting the pulp to any substantial pressure and then nitrating the pulp.

9. The method of producing nitratedcellulose from yellow pine wood which includes extracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizin the pulp, dispersing the pulp in water with agitation, washing the pulp, dewatering the pulp, picking the pulp, drying without subjecting the pulp to any substantial pressure and then nitrating the pulp.

10. The method of producing nitrated cellulose from yellow pine wood which includes extracting rosin, turpentine and pine oil from the wood, pulping the extracted wood, bleaching the pulp, incompletely mercerizing the pulp, dispersing the pulp in water with agitation, washing the pulp, treating the pulp with a mixture of oxalic and sulphuric acids and sodium fluoride for the removal of ash therefrom, dewatering the pulp, picking the pulp, drying without subjecting the pulp to any substantial pressure and then nitrating the pulp.

CARL J OHAN NORDENSWAN.

RAY F. SCHLAANSTINE. 

